Now a new report from The Wall Street Journal (subscription required) shows the impressive results such incentives have had on electric-car sales in Atlanta.

The Georgia capital has the second highest number of electric-vehicle registrations among major U.S. cities, just behind San Francisco.

That still represents a small fraction--just 2.1 percent--of total registrations in Atlanta, but it's more than five times the national average.

The policies primarily benefit the Nissan Leaf, assembled just 230 miles away in Smyrna, Tennessee. While Atlanta has been the Nissan's top market for the past eight months, the Georgia tax credit only applies to fully-electric vehicles, so the range-extended electric Chevrolet Volt doesn't qualify.

Meanwhile, Tesla Motors' sales in Georgia are capped at 150 units per year under an exemption to an auto-dealer registration law, which normally prohibits the sale of cars by manufacturers.

Buyers that do qualify for the state and local incentives stand to save a lot of money. One Atlanta dealer estimates that customers effectively pay $28 per month on a two-year Leaf lease--once per-mile fuel savings and the $5,000 Georgia tax credit are factored in.